A film forming process for forming a film on a substrate accommodated in a process chamber may be performed as one process in manufacturing a semiconductor device. When the film forming process is performed, deposits adhere to the interior of the process chamber. Thus, after the film forming process is performed, a cleaning gas may be supplied into the process chamber in order to perform a cleaning process to remove deposits that adhere to the interior of the process chamber.
Deposits adhering to the interior of the process chamber may be removed through a cleaning process, but a very small solid compound may be generated from a reaction between the deposits and the cleaning gas used during the cleaning process.